The catalytic efficiency of Fe–porphyrins supported on multi-walled carbon nanotubes in the oxidation of olefins and sulfides with molecular oxygen

Abstract

A Fe–porphyrin catalyst was anchored covalently onto functionalized multi-walled carbon nanotubes. The heterogeneous catalyst was characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FTIR, UV-Vis spectroscopy and thermogravimetric analysis (TGA). The catalyst loading on the nanotube support was determined by atomic absorption spectroscopy (AAS). The aerobic oxidation of olefins and sulfides under ambient conditions was efficiently enhanced under the influence of the separable nanocatalyst. This oxidation system was found to oxidize various sulfides to sulfones and different olefins to their respective epoxides as major products. Aerobic oxidation generally requires high temperatures and/or long reaction times to occur. However, in this research, the aerobic oxidation of olefins and sulfides was studied in the presence of Fe–porphyrin which was immobilized onto multi-wall carbon nanotubes at room temperature and with a short reaction time of 60 min. The separation and recycling of the catalyst and the byproduct of the oxidant were simple, effective, and economic in this clean oxidation method. FTIR and leaching experiments after seven successive cycles showed that the catalyst was very strongly anchored to the carbon nanotubes.